Automatic stopping mechanism for a motion picture projector

ABSTRACT

A solenoid is energized either by an 80 Hz. signal on the film sound track or by operation of a button on the projector. The solenoid operates a lever which releases a crank arm and allows a cam follower on the latter to engage a spiral cam track on a timing wheel which is rotated by the shutter. Such movement on of the lever also operates switch contacts to deenergize the projector motor and to connect the projection lamp in a dimming circuit. The motor and the means driven thereby including the timing wheel coast as the latter moves the crank arm which in turn moves a stop block into the path of movement of a lug on the shutter thereby to stop the latter in an open position. A manually operated start mechanism simultaneously disengages the stop member from the shutter lug, energizes the projector motor and disconnects the projection lamp from the dimming circuit.

United States Patent Zahradnik et al.

[ 5] Mar. 7, 1972 [54] AUTOMATIC STOPPING MECHANISM FOR A MOTION PICTURE PROJECTOR [72] Inventors: George J. Zahradnik, Wheaton; Arthur A.

Pudark, Evanston, both of Ill.

[731' Assignee: A. B. Dick Company, Niles, Ill. 22 Filed: July 31, 1970 21] Appl. No.: 59,933

3,466,124 9/1969 Geisman et al. ..352/l77 X Primary Examiner-Donald O. Woodiel Attorney-McDougall, Hersh & Scott [57] ABSTRACT A solenoid is energized either by an 80 Hz. signal on the film sound track or by operation of a button on the projector. The

solenoid operates a lever which releases a crank arm and allows a cam follower on the latter to engage a spiral cam track on a timing wheel which is rotated by the shutter. Such movement on of the lever also operates switch contacts to deenergize the projector motor and to connect the projection lamp in a dimming circuit. The motor and the means driven thereby including the timing wheel coast as the latter moves the crank arm which in turn moves a stop block into the path of movement of :1 lug on the shutter thereby to stop the latter in an open position. A manually operated start mechanism simultaneously disengages the stop member from the shutter lug, energizes the projector motor and disconnects the projection lamp from the dimming circuit.

14 Claims, 24 Drawing Figures PATENTEDMAR 7 L972 8, 647. 2 88 sum 2 or 8 PATENTEDMAR 1 I972 SHEET 3 (IF 8 PAIENTEBMAR 71912 SHEET 7 BF 8 AUTOMATIC STOPPING MECHANISM FOR A MOTION PICTURE PROJECTOR BACKGROUND OF THE INVENTION In the operation of motion picture projectors, especially projectors used as teaching or instructional aids, it is desirable to be able to stop the projection sequence with a single frame in the projection gate. Such frame may contain printed matter or other subject matter for which still projection is desired.

I-Ieretofore, moving picture projectors have been provided with means for achieving so-called still projection. In one type of such known projector, means are provided for disengaging the film drive claw from the film. According to this technique, the film stops at random, requiring the operator, in almost every instance, to operate a framing control to bring a single frame into proper alignment in the projection gate. Another known method for achieving still projection is simply to provide switch means for deenergizing the projection motor .which will result not only in stopping of film movement, but

also in stopping of the shutter. According to this technique,

the operator must operate a shutter control for manually rotating the shutter to an open position since the latter stops at random following'deenergization of the motor.

The present invention is directed toward projector construction which will automatically stop the projection sequence with a single film frame properly positioned in the projection gate and with the shutter in the open position. The construction according to the present invention may be operated at will by a button on the projector or in a programmed manner by a signal on the sound track of the motion picture film.

OBJECTS THE INVENTION A primary object of the present invention is the provision of new and improved moving picture construction for stopping a projection sequence and projecting a single film frame.

Another object of the present invention is the provision of new and improved moving picture projector construction for stopping a projection sequence and projecting a single frame, which construction includes timing means for stopping the shutter in an open position after the latter has been allowed to coast subsequent to deenergizing of the projector drive motor.

Another object of the present invention is the provision of automatic stopping mechanism of the type described which may be actuated either by a control on the projector or by a signal on the sound track of the film.

Still another object of the present invention is the provision of automatic stopping mechanism of the type described which will always stop the film with a single frame in the gate and with the shutter in an open position and which does not require manual operation of a framing control or a shutter adjustment member.

Yet another object of the present invention is the provision of a moving picture projector embodying the aforesaid stopping mechanism and also embodying starting mechanism for releasing the stopping mechanism, resetting the timing mechanism and energizing the projector motor in a substantially simultaneous manner.

Another object of the present invention is the provision of a moving picture projector according to the foregoing object wherein such starting mechanism does not interfere with operation of the stopping mechanism, regardless of when the starting mechanism is actuated.

These and other objects and advantages of the invention -will become apparent from the accompanying specification disclosing a preferred embodiment shown in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is perspective view of a motion picture projector embodying the present invention;

FIG. 2 is an enlarged top plan view, largely schematic, primarily showing the optical system within the projector;

FIG..3 is an enlarged fragmentary section taken along the line 3-3 of FIG. 1;

FIG. 4 is an enlarged fragmentary section taken along the line 4-4 of FIG. 1;

FIG. 5 is a fragmentary side elevation primarily showing the shutter and the timing mechanism;

FIG. 6 through 10 are side elevations similar to FIG. 5 and showing successive phases of operation of the timing mechanism;

FIG. 11 is a fragmentary side elevation showing a locking member which prevents reverse rotation of the shutter;

FIG. 12 is a section taken along the line l2l2 of FIG. 3;

FIG. 13 is a plan view taken along the line l3l3 of FIG. 10;

FIG. 14 is a section taken along the line 14 14 of FIG. 12, but showing only the stop block member;

FIG. 15 is an end view taken along the line 15-15 of FIG. 14;

FIG. 16 is a section similar to FIG. 4 showing the timing mechanism in a disengaged configuration;

FIGS. 17 through 19 are sections similar to FIG. 16 showing DESCRIPTION OF A PREFERRED EMBODIMENT GENERAL Referring primarily to FIGS. 1 and 2, the present invention is shown for purposes of illustration as embodied in a small, portable, sound movie projector 10 intended primarily as a teaching device. The projector includes a casing having an upper wall 11 mounting a carrying handle 12. The casing has a side wall 13 defining a cavity 14 for detachable reception of a film cartridge 15. This cartridge may be of the type disclosed and claimed in US. Pat. No. 3,5 l4,l95, in the name ofOtto R. Nemeth and assigned to the assignee of this application.

Such cartridge has a cavity or recess for receiving a projection unit 16 containing a projection lamp 17, a condensing lens 18 and a projection lens 19. The cartridge 15 guides the film 20 through the projection gate where the film is engaged by a shuttle claw which may take a variety of forms, all known to those skilled in the art. The drive claw mechanism is shown in block form and designated 21; it will be understood that the drive claw mechanism is driven by cam means from a shaft 22 mounting a shutter 23. A framing knob 24 is associated with the drive claw mechanism to establish proper framing of the images in a manner well known in the art.

The image transparencies are projected to an inclined mirror 25, to another inclined mirror 26 and then to a rear projection screen 27 mounted on the front wall 28 of the projector housing. This optical system forms no part of the present invention; it is shown for purposes of illustration only and may take a variety of forms.

The front wall 28 mounts an on-off knob 30, a picture-hold button 31 and a height-control button 32 for adjusting the position of the front feet 33.

Referring now to FIGS. 3 and 4, the projector includes an electric motor 35 which drives a belt 36 received in an annular groove 37 formed in the shutter 23. The shutter carries a gear 38 in meshing engagement with a larger gear 39, the latter being mounted on a shaft 40. The gear 39 carries a smaller gear 41 in meshing engagement with another gear 42 which carries a film drive sprocket wheel (not shown). The gear 42 also carries a roller (not shown) serving to drive a belt 43, which belt drives another roller 44. The roller 44 carries a friction takeup wheel (not shown) for engagement with the film in the cartridge 15.

The shutter 23 contains a pair of diametrically oppositely disposed openings 46. The shutter is shown in the open position in FIG. 3, i.e., with one of the openings 46 disposed between the portion of the optical light path defined by the mirrors 25 and 26. When the shutter occupies this position, a film transparency is of course being projected and the drive or shuttle claw is disengaged from the film at the projection gate with a singleframe occupying the projection position at such gate, assuming that the film has been properly framed at the 1 beginning of a projection sequence. At this time it should be mentioned that the shutter is rotated in a clockwise direction as indicated by the arrow in FIG. 3.

THE AUTOMATIC STOPPING MECHANISM The automatic stopping mechanism includes a timing wheel 48 rotatably mounted about a shaft 49, the latter being supported by a vertically disposed partition plate 50. This timing wheel includes a continuous formation of peripheral teeth 51 in meshing engagement with the teeth on the gear 38 carried by the shutter. In the embodiment shown for purposes of illustration, the shutter makes three revolutions for every single revolution of the timing wheel 48 This particular 3:1 ratio is not critical, it being only necessary that each revolution of the timing wheel 48 bean aliquot part of the number of revolutions of the shutter for each revolution of the timing wheel. In other words, by way of example, the ratio of revolutions between these two members may be 2: I, 3:1, 4:1, etc.

As best seen in FIGS. and 10, the timing wheel 48 contains a earn track 52 in one face thereof. This cam track has a spiral portion with a starting end 52 formed in a center hub portion 53. The spiral portion of the cam track 52 terminates at 52b and joins an inclined camming surface 52c, the latter joining an arcuate cam track portion 52d.

Referring primarily to FIGS. 3, 5 and 10, a crank arm 55 is pivotally and shiftably mounted adjacent one end thereof about a pin 56, the latter being suitably supported within the projector housing. The crank arm 55 includes a tab portion 57 intermediate the ends thereof, which portion mounts a pin 58 adapted to engage the cam track in the timing wheel 48 and thereby acts as a cam follower. The crank arm includes a rounded portion 59in which one end of a coil spring 60 is received, the other end of such spring being suitably mounted in the projector as best seen in FIG. 3. The spring 60 urges the crank arm in a counterclockwise direction about the pin 56 bringing the pin 58 into abutting engagement with the shaft 49, the engagement between these two members acting as a stop for the crank arm 55 and defining an inoperable or disengaged position for the latter as illustrated in FIG. 3.

The crank arm 55 mounts a camming block 62 on the distal end thereof. As seen in FIG. 4, the crank arm 55 is offset adjacent the pivot axis thereof and is connected with a sleeve 63 rotatably and slidably received on the pin 56. A spring 64 is connected to the crank arm and to a suitable fixed member in the projector for urging the crank arm toward the timing wheel 48. The crank arm is guided in its movement toward and away from the timing wheel by the sliding action of the sleeve 63 on the pin 56. As noted in FIG. 5, the crank arm has an extension 55a, the purpose of which will be explained hereinbelow.

An upstanding portion 66 of the partition plate 50 mounts a pair of pins 67, 68 received in respective openings 69, 70 formed in a stop block 72. A spring 73 has one end secured to a fixed bracket 74 and the other end thereof connected to the stop block for urging the same to an upper or inoperable position as seen in FIG. 5 wherein the lower end of the opening 69 abuts the pin 67 and the left side of the opening 70 abuts the pin 68. As best seen in FIGS. 14 and 15, the stop block 72 mounts a pin 75 extending from one face thereof. The stop block includes an integral projection or stop 76 on the other face thereof, which stop includes an upstanding finger portion 76a.

A locking arm 78 is pivotally mounted at one of its ends on a pin or shaft 79, the latter being fixedly mounted in any suitable manner within the projector. A spring 80 has one end thereof connected to the arm 78 and the other end thereof connected to a bracket 81, which bracket is secured, as by means of a pin 82, to the partition plate 50. The spring 80 urges the locking arm 78 in a clockwise direction and holds the distal end thereof in following engagement with the upper surface of the stop 76 on the stop block 72, such distal end being received between the finger portion 76a and the adjacent face of the stop block as shown in FIG. 13. The arm 78 has a notch in the distal end thereof defining a locking surface 83 (see FIG. I I As will be explained hereinbelow, the timing wheel 48 causes downward timed movement of the stop block 72 and the locking arm 78 for capturing a lug 85 carried by the shutter thereby stopping the latter in the open position.

Referring to FIGS. 4 and 16, a horizontally disposed bracket plate 87, which is suitably supported in the projector, carries a pin 88 pivotally mounting an actuating arm 89 intermediate the ends of the latter. One end of the actuating arm includes a right angle latch member 90 which is normally engaged behind the end 63a of the sleeve 63 for holding the crank arm 55 in the disengaged or inoperable position (as shown in FIG I6) and thereby preventing engagement between the pin 58 and the cam track on the timing wheel 48. The other end of the actuating arm 89 is engaged with the plunger 9l'of a solenoid 92 by a sliding pivot connection; this solenoid is supported by a bracket 93 in turn mounted by the bracket 87. The arm 89 supports a switch actuating plate 95 for engagement with the actuating finger 96 of a microswitch 97. This switch controls the audio output of the projector as well as a delay circuit to be mentioned hereinbelow.

The bracket plate 87 mounts a switch 98. This switch includes a first set of contacts for energizing and deenergizing the projector drive motor 35. The switch 98 includes another set of contacts for alternately connecting the projection bulb 17 in a dimming circuit for reducing the level of illumination of such bulb. The sets of contacts in this switch are simultaneously controlled by an operating finger 96. The distal end of this operating finger is arranged to be engaged by one end of a floating pin 100, the other end of which pin is engaged by the extension 55a on the crank arm. It will be understood this floating pin is suitably mounted for axial reciprocal movement.

The bracket plate 87 includes an opening 102 journaling a reduced-end portion of a sleeve 103, the other end of such sleeve being defined by a reduced-end portion suitably journaled. The sleeve 103 includes, intermediate the ends thereof, a threaded, diametrically extending, through bore in threading engagement with the threaded portion of a catch pin 105. It will be understood this pin is thereby mounted for swinging movement back and forth between the positions indicated in FIGS. 4 and 16. When the pin 105 is in the position shown in FIG. 4, the end 105a thereof engages the extension 55a on the crank arm for holding the same in its engaged position with the pin 58 received in the cam track formed in the timing wheel 48. The threaded engagement between the catch pin 105 and the sleeve 103 permits post-assembly adjustment of the former to compensate for production tolerances.

The projector mounts another horizontally disposed bracket plate 107. A coil spring 108 has one end thereof secured in an aperture in this bracket plate and the other end thereof connected to the actuating arm 89 for urging the same to the deenergized position shown in solid lines in FIG. 16. Another coil spring 109 has one of its ends secured in an aperture in the bracket plate 107 and its other end connected to the head l05b of the catch pin 105.

An electrical circuit for the automatic stop mechanism according to the present invention is preferably of the type disclosed and claimed in the copending application of Mark A. Hutner assigned to the assignee of the present application. The Hutner circuit provides for energization of the solenoid 92 by manual actuation of the picture-hold button 3] during a projection sequence or by an 80 Hz. signal impressed on the sound track of the movie film. In other words, the automatic stop mechanism of the present invention may be operated at any time by depressing the button 31 or automatically in a programmed manner by signals on the sound track which are impressed thereon in predetermined spaced relation from the frames for which still projection is desired. Reference may be had to the Hutner application for a detailed explanation and description of the circuit used with the present invention. It is sufficient for purposes of understanding the present invention to refer to the electrical schematic of FIG. 24 herein.

OPERATION OF THE STOPPING MECHANISM Assume that the projector is in normal operation wherein the solenoid is in the deenergized position as shown in FIG. 16, the latch 90 is in engagement with the sleeve end 63a thereby acting in opposition to the spring 64 and holding the crank arm away from the timing wheel 48 with the pin 58 in adjacent spaced relation with the hub 53 on the timing wheel. During such operation, the timing wheel will of course be rotating at a uniform rate as the latter is directly driven from the shutter.

When the solenoid is actuated, the arm 89 i is rotated clockwise withdrawing the latch 90 from the sleeve 63 allowing the spring64 to pull the crank arm 55 toward the timing wheel whereupon the end of the pin 58 will engage the rotating hub portion 53 of the timing wheel. The pin 58 will drop into the leading end 52a of the spiral cam track as soon as the timing wheel rotates sufficiently to bring such portion into alignment with the follower pin 58, whereupon the spring 64 will snap the follower pin into the cam track as shown in FIG. 4. As noted in FIG. 16, when the crank arm was in the inoperable or disengaged position, the catch pin 105 was in engagement with the end edge of the crank arm 55, the spring 109 serving to maintain such engagement between the crank arm and the catch pin. When the crank arm was allowed to be moved toward the timing wheel under the influence of the spring 64, the spring 109 caused the end 105a of the catch pin to snap behind the extension 55a of the crank arm thereby preventing disengagement of the follower pin 58 from the cam track 52. counterclockwise rotation of the catch pin about the axis of the sleeve 103 is limited by a tripping member to be explained below.

The aforedescribed movement of the crank arm allows the floating pin 100 to shift in a corresponding direction thereby in turn allowing the switch actuating finger 99 to deflect (under its own energy) for operating the switch contacts in the switch 98. These contacts deenergize the projector drive motor 35 and connect the projection bulb 17 in a dimming circuit. In other words, the motor 35 is deenergized substantially simultaneously with commencement of a timing cycle initiated by engagement of the follower pin 58 in the starting end 52a of the cam track. The projection bulb is dimmed at this time to compensate for the increased brilliance that would result due to the shutter being stationary during still projection.

The aforedescribed movement of the arm 89 actuates the switch 97 by reason of the engagement between the plate 95 and the operating finger 96. This switch turns off the audio output and brings a delay circuit into operation to prevent the solenoid from being energized by false signals during start up of the machine after still projection. Refere'nce should be had to the aforementioned Hutner application for a description and understanding of this delay circuit.

The action of the solenoid is only momentary, and upon deenergization of such solenoid the spring 108 acts to urge the actuating arm 89 in a counterclockwise direction toward the solid line position of FIG. 16 until the latch 90 engages the side of the sleeve 63-the latch 90 is not permitted at this time to enter the space behind the sleeve 63.

The deenergized motor and the various members driven thereby, including the shutter and timing wheel, coast and of course decelerate. During this rotation of the timing wheel, the crank arm 55 is swung in a clockwise direction about the pin 56 by reason of the follower pin 58 following or riding along the spiral cam track 52. At this time, the stop member 72 and locking arm 78 will be in their inoperable positions as shown in FIG. 5; the stop 76 will be above the circular path of travel of the shutter lug 85 so as to avoid interference with shutter movement.

As the crank arm 55 continues its upward travel, the camming block 62 comes into engagement with the pin 75 on the stop block as shown in FIG. 7. Continued upward movement of the crank arm causes the stop block 72 to rock about the pin 67 as shown in FIG. 8 (this rocking movement being permitted by the shape of the opening 70) until the follower pin 58 reaches the portion 52b of the cam track whereupon the cam block 62 will have passed beyond the pin 75 thereby allowing the spring 73 to return the stop block 72 to its initial position as shown in FIG. 9. As the timing wheel continues to coast,'the inclined cam surface 520 causes the crank arm to reverse its direction of movement and to commence rotating in a counterclockwise direction whereby the underside of the cam block 62 will be brought into engagement with the pin 75 for urging the stop block downwardly to the position shown in FIG. 10 as the followerpin 58 enters the arcuate portion 52d of the cam track. This movement of the stop block 72 brings the stop 76 downwardly into the path of movement of the lug 85 on the shutter. When the stop 76 reaches this lower or operable position, the shutter lug 85 will have passed a positionadjacent the stop and will be continuing to coast along with the shutter in a clockwise direction.

Such lowering movement of the stop block will allow the locking arm 78 to drop to the position shown in FIG. 10. As the shutter continues to coast, the lug 85 will now engage the underside of the locking arm and lift the same slightly until the lug 85 passes beyond the lock surface 83, whereupon the spring 80 will return the locking arm 78 with the distal end 7 thereof again resting on the stop 76. The shutter lug will now engage the stop 76 thereby stopping the shutter with the lug captured between the stop 76 and the locking surface 83, the latter serving to prevent rebound movement of the shutter and ensuring stopping of the latter with one of the openings 46 properly positioned in the optical path for still projection of a single film frame. The shutter is now actually locked against rotation in either direction by reason of the positive engagement between all members of the timing mechanism including the crank arm 55 and catch pin 105.

Stopping of the shutter will also cause stopping of the timing wheel as well as the other members which are driven by the projection drive motor. The motor and the various means driven thereby have sufficient inertia to ensure that the timing wheel 48 will be rotated an adequate number of revolutions to complete the timing cycle and bring the shutter lug 85 into its captured position between the stop 76 and the locking surface 83. If necessary, weights can be added to the motor shaft to ensure an adequate amount of coasting. The various parts are designed to ensure that the timing wheel and shutter coast a sufficient number of revolutions to complete the timing cycle, but do not have an angular velocity so great that high impact foreces result when the shutter lug 85 engages the stop 76. In this connection, the stop member 72 is preferably formed of energy absorbing or vibration dampening material, such as a celanese plastic material, for example.

THE STARTING MECHANISM The mechanism for starting the projector and resuming normal moving projection includes an operating arm 112 having one of its ends extending through a slot 113 in the projection casing and mounting a knob 114. The arm is pivotally mounted on the bracket 107 by a pivot pin 115. A spring 116 is coiled one or more times around this pin and has one end thereof received in a downwardly extending ear 107a formed integrally on the bracket plate. The other end of this spring wire is engaged by a downwardly extending ear 112a integral with the operating arm. The spring 116 urges the operating arm 112 in a clockwise direction normally holding a stop ear 112b in abutting engagement with an edge 107b of the bracket plate.

The arm 112 has a finger portion 112c pivotally mounting, as by means of a pin 117, a pawl 118, the latter being best shown in FIG. 23. A spring 119 is wound one or more times around a bushing 120 which is supported by the pin 117. One end of the spring 119 engages the ear 11%; the other end of this spring is received in an aperture 118a formed in the pawl thereby urging the pawl in a counterclockwise direction about the pin 117 and holdingan upwardly extending stop member 118!) in abutting engagement with an edge surface 112d formed on the distal end of the finger 112c. As seen in FIG. 23, the pawl has an edge surface 1180.

Bracket plate 107 mounts a pin 122, the latter pivotally mounting a right angle bracket 123. This bracket has a first leg 123a which includes an upstanding, integral camming surface 123b. This bracket includes another arm 123a having an extension l23d with an upturned end 1232 as best seen in FIG. 20. 'The bracket portions 123d, 12e are arranged to abut the sleeve end 63a forming part of a crank arm for returning the same to the disengaged or inoperable position as will be explained hereinbelow. A spring strip 124 (FIGS. 3 and engages the arm portion l23d urging the same into abutting engagement with a depending portion 107c of the bracket 107. The spring strip 124 is suitably secured to the bracket portion 107e, as by a fastener 124a.

The bracket 107 mounts a pin 125 received in a slot 1126 of a cocking arm 127. This arm has an integral, downwardly extending cam surface 127a for sliding or camming engagement with the cam surface 123b as will be explained herein. A coil spring 128 has one of its ends connected to a pin 129 mounted from-the bracket plate 107 and the other of its ends connected to an upstanding ear 127b formed integrally on the cocking arm 127. This spring normally urges the cocking arm 127 to the position shown in FIGS. 4 and 16 wherein one end of the slot 127 engages the pin 125 and a side edge of the cocking arm abuts a yieldable stop or bumper 130, the latter being supported from the bracket plate 107. The arm 127 includes an edge surface 1270 for sliding engagement with the pawl edge surface 1180 as will be explained below.

A tripping arm 132 is mounted from the sleeve 103 for pivoting movement independently of the latter. This arm includes an upstanding ear 132a for abutting engagement with the catch pin 105, such abutting engagement being brought about by the action of the spring 109. The tripping arm 132 includes an upstanding ear 132b arranged to be engaged by end edges of both camming surfaces 123k and 127a. A tab l32c extends integrally from the ear 132b. A coil spring 133 has one end thereof connected to the tripping arm 132 and the other end thereof connected to the bracket 107; this spring urges the tripping member in a counterclockwise direction normally holding the ear 132b in abutting engagement with the edge of the camming surface l23b.

OPERATION OF THE STARTING MECHANISM As mentioned above, the operating arm 112 normally occupics the position shown in FIGS. 4 and 16. Assume that the projector has been stopped and that the various parts of the timing mechanism are in the positions as explained above.

As the start button is actuated for pivoting the am 112 in a counterclockwise direction, the pawl surface 118c comes into abutting engagement with the cocking arm edge surface 127s. Continued counterclockwise movement of the arm 112 will cause the cam surface 127a to engage and ride along the cam surface [23b (FIG. 17) thereby elongating and storing energy in the coil spring 128. It should be mentioned at this time that the bracket 123 is not free to rotate as the end 123e thereof engages the sleeve end 63a, movement of the latter being restrained by reason of the engagement between the catch pin end 1050 with the crank arm extension 55a.

After the arm 127 is fully cocked, the leading end of the cam surface 1270 comes into engagement with the car 1321; of

the tripping arm 132. Continued counterclockwise movement of the arm 112 will result in clockwise rotation of the tripping arm 132. This rotation of the tripping arm will result in corresponding rotation of the catch pin by reason of the engagement between the latter and the ear 132a. Accordingly, further movement of the operating arm 112 will result in the catch pin 105 being tripped or rotated in a clockwise direction (FIG. l8) whereupon the end 105a will be disengaged from the crank arm extension 55a. During this tripping movement of the arm 132, the ear 132b will separate from the camming surface l23b as seen in FIG. 18. At this instant of tripping, the stored up energy in the spring 128 is transferred to the bracket 123 by reason of engagement of the camming surfaces 172a, 123b, thereby to rotate the bracket 123 about the pin 122 in a snapaction fashion for abruptly disengaging the crank arm (and follower pin 58) from the timing wheel 48. In imparting this rotation to the bracket 123, the edge 127c of the cocking arm slides along the edge surface 118a of the pawl 118 until it clears the latter whereupon the spring 128 brings the cocking arm into engagement with the bumper 130. After the bracket 123 has been swung counterclockwise in this snap-action manner, the spring strip 124 will immediately return the bracket 123 clockwise to its normal position free of the sleeve end 63a. This prompt return movement of the bracket 123 ensures that the stopping mechanism may commence a timing cycle should the solenoid 92 be energized immediately after operation of the starting mechanism.

The just described movement of the crank arm will also result in disengagement of the cam block 62 from the pin on the stop block 72. The spring 60 will immediately return the crank arm 55 to the inoperable or disengaged position as shown in FIG. 3. At the same time, the spring 73 will return the stop block to its upper or inoperable position whereupon the lug on the shutter will be free.

As the crank arm 55 is snapped to the disengaged or inoperable position, the floating pin will be shifted by reason of the engagement of the latter with the crank arm extension 55a. This movement of the floating pin deflects the switch operating finger 99 for energizing the motor and for switching out the dimming circuit returning the projection lamp 17 to full brilliance. The motor will now commence rotation of the various parts including the shutter, the latter being free to rotate since the stop 76 is not in the path of travel of the shutter lug 85.

It should be apparent that energizing the motor occurs substantially simultaneously with freeing of the shutter lug 85. By reason of the fast snap action of the crank arm in separating from the timing wheel which in turn causes the stop 76 to be abruptly pulled out of the path of travel of the shutter lug, the shutter will always be free to rotate upon energization of the motor thereby to prevent damage or a jamming situation which would occur should the motor be energized prior to the time the shutter is free to rotate.

As the crank arm 55 is returned to the inoperable or disen gaged position, the spring 108 acts to rotate the actuating arm 89 in a counterclockwise direction withdrawing the solenoid plunger and inserting the latch 90 behind the sleeve end 63a thereby to hold the crank arm in such inoperable position. At this time, the spring 109 acts to hold the catch pin in abutting engagement with the end edge of the crank arm extension 55a as shown in FIG. 16. Return movement of the actuating arm 89 allows the actuating arm 96 of switch 97 to deflect thereby turning on the audio output and the delay circuit.

Upon return of the crank arm 55 to the disengaged or inoperable position, the operating member 114 is ordinarily immediately released allowing the spring 116 to return the operating arrn 112 to the inoperable position as shown in FIGS. 4 and 16. The spring 119 allows movement of the pawl 118 relative to the arm 112 (FIG. 19) to facilitate movement of such pawl over the camming surface 127a. The tripping arm 132 has already been restored to its initial position with the ear 13211 in abutting engagement with the end of the camming surface l23b by the action of the spring 133. It will be apparent that the various parts have been positioned for another cycle of operation of the starting mechanism prior to return movement of the arm 112.

It should be understood that the starting mechanism will operate to disengage the timing members in the snap-action manner described above even if the motor and timing gear are still coasting. Further, the snap-action movement of the bracket 123 will occur should the operator actuate the starting mechanism even though the projector has not been stopped (of course there would be no reason for the operator to do so). Should the starting mechanism be operated under this condition, the tab 1320 on the tripping arm acts as a latch to prevent movement of the bracket 123 until the cocking arm 127 has been moved to such an extent that the leading edge of the camming surface 127a abuts the ear 132b and disengages the tab 132c from the camming surface l23b. At the instant of disengagement of the tab 1320 from the camming surface 123b, the stored up energy in the spring 128 is transferred to the bracket 123 through the interengagement of camming surfaces 123b, 127a for imparting the snap-action movement to the bracket 123b. The cocking arm 127 will be returned into engagement with the bumper 130 and the spring strip 124 will immediately return the bracket 123 to its normal position free of the sleeve end 63a thereby to permit movement of the crank arm 55 should the solenoid 92 be energized.

Because of the snap-action movement of the bracket 123 and its immediate return by the spring 124, it is virtually impossible to operate the starting mechanism so as to cause a jam or to interfere with a programmed stop. Should the bracket 123 be snapped counterclockwise at the instant of energization of the solenoid 92 in response to an 80 Hz. signal (it is very unlikely that this condition would occur) a programmed stop might be missed. In this unlikely event, if the operator heard the solenoid actuate, he could immediately actuate the picture-hold button 31 which would result in stopping of the projector.

As far as operation of the starting mechanism is concerned, it is important to realize that the snap action of the bracket 123 and its immediate return by the spring 124 are independent of the manner in which the arm 112 is operated. Since this always produces rapid shifting movement of the crank arm 55, it is virtually impossible for the crank arm to be in an intermediate position with the pin 58 partially engaged with the cam track and with the motor still energized due to insufficient movement of the floating pin 100 which would of course very likely result in damage to the projector as the shutter would still be driven at its normal speed at the instant of impact of the lug 85 with the stop 76.

We claim:

1. In a motion picture projector, the construction for stopping a projection sequence and projecting a single film frame comprising:

a. a motor and means driven thereby including a shutter;

b. a mechanical timing mechanism operated by said means for causing timed movement of an element between inoperable and operable positions, which element in the operable position thereof serves to stop said shutter in an open position of the latter; and

c. means for actuating said timing mechanism and for substantially simultaneously deenergizing said motor whereby the latter and said means driven thereby coast until movement of the shutter is arrested by said element.

2. In a motion picture projector, the construction for stopping a projection sequence and projecting a single film frame comprising:

a. a motor and means driven thereby, which means include a shutter and a first formation which moves during movement of the shutter and which occupies a predetermined position when said shutter is in an open position;

b. a mechanical timing mechanism which is driven by said means, which mechanism includes a second formation and a timing member for causing movement of said second formation between an inoperable position and an operable position, said second formation, in the operable position thereof, serving to engage said first formation thereby to stop the same in said predetermined position; and 0. means for actuating said timing mechanism and for substantially simultaneously deenergizing said motor whereby the latter and said means driven thereby coast until said second formation engages said first formation. 3. The construction according to claim 2 wherein said timing member is defined by a wheel having a cam track at least a portion of which is spiral in form, said second formation being moved from its inoperable position to its operable position by an element having a cam follower arranged to engage said cam track.

4. The construction according to claim 3 further defined by gear means for rotating said timing wheel in response to rotation of said shutter, said gear means serving to rotate said timing wheel such that one revolution of the latter constitutes an aliquot part of the number of shutter revolutions for each revolution of the timing wheel.

5. The construction according to claim 2 further defined by locking mechanism including an arm moved between operable and inoperable positions by said second formation in response to corresponding movement of the latter, said arm, in the operable position thereof, serving to cooperate with said second formation to capture said first formation in said predetermined position thereof.

6. The construction according to claim 2 wherein said actuating means includes switch means, said switch means having a first set of contacts to energize and deenergize said motor and a second set of contacts for connection in a dimming circuit for the projection lamp.

7. The construction according to claim 1 further defined by, starting means cooperating with said actuating means for returning said element to its inoperable position and for substantially simultaneously energizing said motor.

8. The construction according to claim 2 further defined by, starting means cooperating with said actuating means for disengaging said second formation from said first formation and for substantially simultaneously energizing said motor.

9. The construction according to claim 2 further defined by:

a. said actuating means including catch means having a catch member adapted for engagement with said timing mechanism for positively holding said second formation in its operable position;

b. first biasing means urging said second formation toward its inoperable position;

c. starting means cooperating with said actuating means for returning said second formation to its inoperable position and for substantially simultaneously energizing said motor, which starting means includes an operating arm movable back and forth between first and second positions;

d. said starting means including an element adapted, upon movement in one direction, for engagement with said timing mechanism to disengage said second formation from said first formation, movement of said element in said one direction being normally restrained by said catch member;

e. said starting means including second biasing means actuated upon movement of said operating arm from said first position to said second position to apply a force to said element tending to urge the latter in said one direction; and

f. said starting means having a release member adapted to engage said catch means as said operating arm reaches its second position thereby to release the catch means and allow said second biasing means abruptly to move said element in said one direction whereupon said second formation is disengaged from said first formation and allowed to return to its inoperable position by said first biasing means.

10. In a motion picture projector, the construction for stopping a projection sequence and projecting a single film frame comprising:

a. a motor and means driven thereby, which means include a shutter and a formation which moves during movement of the shutter and which occupies a predetermined position when said shutter is in an open position;

b. a timing wheel driven by said means such that one revolution of the latter constitutes an aliquot part of the number of shutter revolutions for each revolution of said wheel, which wheel includes a cam track having a starting end;

c. a stop member and means mounting the same for movement back and forth between inoperable and operable positions, said stop member, in the operable position thereof, serving to engage said formation thereby to stop the same in said predetermined position;

d. a crank arm mounted for movement back and forth between engaged and disengaged positions, which arm mounts a follower for camming engagement with said cam track;

e. means normally holding said crank arm in its disengaged position with said follower in adjacent spaced relation with the starting end of said cam track;

f. actuating means for moving said crank arm to its engaged position thereby causing said follower to engage said cam track at said starting end thereof, rotation of said timing wheel serving to move said crank arm from a first position to a second position by the action of said follower and said cam track;

g. said crank arm being associated with said stop member for moving the latter to its operable position during movement of said crank arm to its second position; and

h. said actuating means including switch actuating means for deenergizing said motor substantially simultaneously with movement of said crank arm to its engaged position whereby said motor and said means driven thereby coast until movement of said formation is arrested by said stop member.

11. The construction according to claim wherein said formation is carried by said shutter.

12. The construction according to claim 10 further defined by a locking arm mounted for movement back and forth between operable and inoperable positions in response to corresponding movement of said stop member, said locking arm having an abutment surface cooperating with said stop member when the latter and said arm are in said operable positions thereby to capture said formation.

13. The construction according to claim 10 further defined a. biasing means connected with said stop member and serving to. move the latter to its inoperable position in response to movement of said crank arm from its engaged position to its disengaged position; and

b. starting means associated with said actuating means for disengaging said stop member from said formation and for substantially simultaneously energizing said motor, said starting means including releasable catch means for returning said crank arm to its disengaged position by a snap action thereby allowing said biasing means abruptly to move said stop member to the inoperable position thereof.

14. The construction according to claim 13 further defined a. said starting means including an operating arm movable back and forth between first and second positions;

b. said releaseable catch means including a catch member arranged to engage said crank arm for holding the same in said engaged position thereof;

. said starting means including a bracket arranged to move in a release direction and during such movement to contact said crank arm for moving the latter to said disenga ed osition thereof; d. ot er lasing means for applying a force to said bracket urging the latter in said release direction in response to movement of said operating arm from said first position to said second position; and

e. tripping means actuated by said operating arm as the latter reaches its second position for disengaging said catch member from said crank arm thereby allowing said bracket to snap said crank arm from its engaged position to its disengaged position.

. UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated 7 March 1972 Patent No. 3,647, 288

Inventor) G, J. Zahradnik a; A. A. Pudark' It is certified that error appears in, the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Column 4, line 38, "96" shotlld read 99;

column 7, line 28, "1126" should read -l26--.

Signed and sealed this 25th day of'July 1972 (SEAL) Attest:

EDL'JARI) M.FLE'1"CH\1R,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patents UNITED STATES PATENT 'GFFICE CERTIFICATE OF CORECTION Dated 7 March 1972 Patent No.

Inventor) G. J. Zahradnik SE A. A. Pudark It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 38, "96" should read 99-;

"1126" should read --l26-.

column 7, line 28,

Signed and sealed this 25th day of Jul; 1972.

(SEAL) Attest:

EDWARD M.FLETCHE;R,JR. ROBERT GOTI'SCHALK Commissioner of Patents Attesting Officer 

1. In a motion picture projector, the construction for stopping a projection sequence and projecting a single film frame comprising: a. a motor and means driven thereby including a shutter; b. a mechanical timing mechanism operated by said means for causing timed movement of an element between inoperable and operable positions, which element in the operable position thereof serves to stop said shutter in an open position of the latter; and c. means for actuating said timing mechanism and for substantially simultaneously deenergizing said motor whereby the latter and said means driven thereby coast until movement of the shutter is arrested by said element.
 2. In a motion picture projector, the construction for stopping a projection sequence and projecting a single film frame comprising: a. a motor and means driven thereby, which means include a shutter and a first formation which moves during movement of the shutter and which occupies a predetermined position when said shutter is in an open position; b. a mechanical timing mechanism which is driven by said means, which mechanism includes a second formation and a timing member for causing movement of said second formation between an inoperable position and an operable position, said second formation, in the operable position thereof, serving to engage said first formation thereby to stop the same in said predetermined position; and c. means for actuating said timing mechanism and for substantially simultaneously deenergizing said motor whereby the latter and said means driven thereby coast until said second formation engages said first formation.
 3. The construction according to claim 2 wherein said timing member is defined by a wheel having a cam track at least a portion of which is spiral in form, said second formation being moved from its inoperable position to its operable position by an element having a cam follower arranged to engage said cam track.
 4. The construction according to claim 3 further defined by gear means for rotating said timing wheel in response to rotation of said shutter, said gear means serving to rotate said timing wheel such that one revolution of the latter constitutes an aliquot part of the number of shutter revolutions for each revolution of the timing wheel.
 5. The construction according to claim 2 further defined by locking mechanism including an arm moved between operable and inoperable positions by said second formation in response to corresponding movement of the latter, said arm, in the operable position thereof, serving to cooperate with said second formation to capture said first formation in said predetermined position thereof.
 6. The construction according to claim 2 wherein said actuating means includes switch means, said switch means having a first set of contacts to energize and deenergize said motor and a second set of contacts for connection in a dimming circuit for the projection lamp.
 7. The construction according to claim 1 further defined by, starting means cooperating with said actuating means for returning said element to its inoperable position and for substantially simultaneously energizing said motor.
 8. The construction according to claim 2 further defined by, starting means cooperating with said actuating means for disengaging said second formation from said first formation and for substantially simultaneously energizing said motor.
 9. The construction according to claim 2 further defined by: a. said actuating means including catch means having a catch member adapted for engagement with said timing mechanism for positively holding said second formation in its operable position; b. first biasing means urging said second formation toward its inoperable position; c. starting means cooperating with said actuating means for returning said second formation to its inoperable position and for substantially simultaneously energizing said motor, which starting means includes an operating arm movable back and forth between first and second positions; d. said starting means including an element adapted, upon movement in one direction, for engagement with said timing mechanism to disengage said second formation from said first formation, movement of said element in said one direction being normally restrained by said catch member; e. said starting means including second biasing means actuated upon movement of said operating arm from said first position to said second position to apply a force to said element tending to urge the latter in said one direction; and f. said starting means having a release member adapted to engage said catch means as said operating arm reaches its second position thereby to release the catch means and allow said second biasing means abruptly to move said element in said one direction whereupon said second formation is disengaged from said first formation and allowed to return to its inoperable position by said first biasing means.
 10. In a motion picture projector, the construction for stopping a projection sequence and projecting a single film frame comprising: a. a motor and means driven thereby, which means include a shutter and a formation which moves during movement of the shutter and which occupies a predetermined position when said shutter is in an open position; b. a timing wheel driven by said means such that one revolution of the latter constitutes an aliquot part of the number of shutter revolutions for each revolution of said wheel, which wheel includes a cam track having a starting end; c. a stop member and means mounting the same for movement back and forth between inoperable and operable positions, said stop member, in the operable position thereof, serving to engage said formation thereby to stop the same in said predetermined position; d. a crank arm mounted for movement back and forth between engaged and disengaged positions, which arm mounts a follower for camming engagement with said cam track; e. means normally holding said crank arm in its disengaged position with said follower in adjacent spaced relation with the starting end of said cam track; f. actuating means for moving said crank arm to its engaged position thereby causing said follower to engage said cam track at said starting end thereof, rotation of said timing wheel serving to move said crank arm from a first posItion to a second position by the action of said follower and said cam track; g. said crank arm being associated with said stop member for moving the latter to its operable position during movement of said crank arm to its second position; and h. said actuating means including switch actuating means for deenergizing said motor substantially simultaneously with movement of said crank arm to its engaged position whereby said motor and said means driven thereby coast until movement of said formation is arrested by said stop member.
 11. The construction according to claim 10 wherein said formation is carried by said shutter.
 12. The construction according to claim 10 further defined by a locking arm mounted for movement back and forth between operable and inoperable positions in response to corresponding movement of said stop member, said locking arm having an abutment surface cooperating with said stop member when the latter and said arm are in said operable positions thereby to capture said formation.
 13. The construction according to claim 10 further defined by: a. biasing means connected with said stop member and serving to move the latter to its inoperable position in response to movement of said crank arm from its engaged position to its disengaged position; and b. starting means associated with said actuating means for disengaging said stop member from said formation and for substantially simultaneously energizing said motor, said starting means including releasable catch means for returning said crank arm to its disengaged position by a snap action thereby allowing said biasing means abruptly to move said stop member to the inoperable position thereof.
 14. The construction according to claim 13 further defined by: a. said starting means including an operating arm movable back and forth between first and second positions; b. said releaseable catch means including a catch member arranged to engage said crank arm for holding the same in said engaged position thereof; c. said starting means including a bracket arranged to move in a release direction and during such movement to contact said crank arm for moving the latter to said disengaged position thereof; d. other biasing means for applying a force to said bracket urging the latter in said release direction in response to movement of said operating arm from said first position to said second position; and e. tripping means actuated by said operating arm as the latter reaches its second position for disengaging said catch member from said crank arm thereby allowing said bracket to snap said crank arm from its engaged position to its disengaged position. 